YAZ User's Guide and Reference
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# Records

A record object is a retrieval record on the client side - created from result sets.

         void ZOOM_resultset_records (ZOOM_resultset r,
                                      ZOOM_record *recs,
                                      size_t start, size_t count);
         ZOOM_record ZOOM_resultset_record (ZOOM_resultset s, size_t pos);

         const char *ZOOM_record_get (ZOOM_record rec, const char *type,
                                      size_t *len);

         ZOOM_record ZOOM_record_clone (ZOOM_record rec);

         void ZOOM_record_destroy (ZOOM_record rec);

References to temporary records are returned by functions `ZOOM_resultset_records` or `ZOOM_resultset_record`.

If a persistent reference to a record is desired `ZOOM_record_clone` should be used. It returns a record reference that should be destroyed by a call to `ZOOM_record_destroy`.

A single record is returned by function `ZOOM_resultset_record` that takes a position as argument. First record has position zero. If no record could be obtained NULL is returned.

Function `ZOOM_resultset_records` retrieves a number of records from a result set. Parameter start and count specifies the range of records to be returned. Upon completion array recs[0], ..recs[count-1] holds record objects for the records. The array of records recs should be allocated prior the call `ZOOM_resultset_records`. Note that for those records that couldn't be retrieved from the target recs[ ..] is set to NULL.

In order to extract information about a single record, `ZOOM_record_get` is provided. The function returns a pointer to certain record information. The nature (type) of the pointer depends on the parameter, type.

The type is a string of the format:

form[; charset=from[,to]]

where form specifies the format of the returned record, from specifies the character set of the record in its original form (as returned by the server), to specifies the output (returned) character set encoding. If charset is not given, then no character set conversion takes place. If to is omitted UTF-8 is assumed.

In addition, for certain types, the length len passed will be set to the size in bytes of the returned information.

The following are the supported values for form.

database

  Database of record is returned as a C null-terminated string. Return type const char *.

syntax

  The transfer syntax of the record is returned as a C null-terminated string containing the symbolic name of the record syntax, e.g. Usmarc. Return type is const char *.

render

  The record is returned in a display friendly format. Upon completion buffer is returned (type const char *) and length is stored in *len.

raw

  The record is returned in the internal YAZ specific format. For GRS-1, Explain, and others, the raw data is returned as type Z_External * which is just the type for the member retrievalRecord in type NamePlusRecord. For SUTRS and octet aligned record (including all MARCs) the octet buffer is returned and the length of the buffer.

xml

  The record is returned in XML if possible. SRW/SRU and Z39.50 records with transfer syntax XML are returned verbatim. MARC records are returned in MARCXML (converted from ISO2709 to MARCXML by YAZ). GRS-1 and OPAC records are not supported for this form. Upon completion, the XML buffer is returned (type const char *) and length is stored in *len.

opac

  OPAC for record is returned in XML.

Most MARC21 records uses the MARC-8 character set encoding. An application that wishes to display in Latin-1 would use

         render; charset=marc8,iso-8859-1

## Z39.50 Protocol behavior

The functions `ZOOM_resultset_record` and `ZOOM_resultset_records` inspects the client-side record cache. Records not found in cache are fetched using Present. The functions may block (and perform network I/O) - even though option async is 1, because they return records objects. (and there's no way to return records objects without retrieving them!).

There is a trick, however, in the usage of function `ZOOM_resultset_records` that allows for delayed retrieval (and makes it non-blocking). By using a null pointer for recs you're indicating you're not interested in getting records objects now.

## SRW Protocol behavior

The ZOOM driver for SRW treats records returned by a SRW server as if they where Z39.50 records with transfer syntax XML and no element set name or database name.

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